Mechanical interlock for circuit breakers



Sept. 15, 1959 R. R. RANSON 2,904,649

' MECHANICAL INTERLOCK FOR CIRCUIT BREAKERS Filed Aug. 22, 1957 ATTORNEYUnited States i atent MECHANICAL INTERLOGK FOR CIRCUIT BREAKERS RichardR. Ranson, Whitefish Bay, Wis.,- assignor to Cutler-Hammer, Inc.,Milwaukee, Wis., acorporation of Delaware I Application August 22, 1957,Serial No. 679,680

7 Claims. (Cl. 200-50) This invention relates generally to interlockmechanisms and more particularly to thosefornuse with adjacently mountedcircuit breakers to connect the latter together in such a manner thatoperation. of one breaker and complex, because they mustbe locatedbehind the breakers and are thus difiicult to install and service, andbecause frequently they are comprised of constituent ele ments of such aspecialized nature that they are only suitable for use with particulartypes of breakers.

Accordingly, it is an object of this invention to-provide improvedinterlock mechanisms for use with'a pair of circut breakers each ofwhich has an operating member movable from one to another positionwhereby the operating members of both breakers may besimultaneouslydisposed in one of said positions but upon movement of either operatingmember to its other position the other operating'member cannot bemovedto its other position untilthe first operating member is returnedto its one position.

Another object is to provide improved interlock mechanisms suitable foruse with a;pair of circuit :breakers which are mountedeither'horizontally or vertically adjacent each other either .in directalignment or slightly displaced therefrom.

Still another object is to provide such interlock mechanisms which maybe employed with a pair of breakers of like or dissimilar construction,provided'both have an operating member movable fromone'to anotherposition.

A further object is to .provide improved interlock mechanisms which aresimple, compact, readily adjustable to meet a variety of conditions,reliable in operation, and economical to manufacture and install.

A still further object is to provide improved interlock mechanisms whichare comprised of a-number of identical parts which may be fashioned fromreadily available raw materials and which may be conveniently massproduced or custom made as the case may be.

Other objects and advantages of the invention will hereinafter becomeapparent.

The accompanying drawing illustrates certain embodiments of theinvention which will now be described, it being understood that theembodiments illustrated-are susceptible of modification with respect tocertain structural details thereof without departing from the scope ofthe appended claims.

In the drawing:

Figure 1 is a front elevational view of two-circuit breakers mountedvertically adjacent each other showing the manner in which they areassociated with the interlockingmechanism when both operating handlesare disposed in downward or off position;

Fig. 2 is a view similar to Fig. 1 but showing the upper breaker handlein downward or ofif: position and the lower breaker handle in upward or.on position;

Fig. 3 is an enlarged elevational view of a portion of the interlockmechanism looking in the direction of the arrows on line 33 of Fig. 1;and

Fig. 4 is an enlarged elevational view of a portion of the interlockmechanism looking in the direction of the arrows on line 4-4 of Fig. 1.

Referring to Figs. 1 and 2, the numerals 11 and 12 designate a pair ofcircuit breakers or switches of identical design and dimensions mountedvertically adjacent each other on a supporting member or panel 13 which,for example, could be the rear wall of a cabinet (not shown) wherein thebreakers are enclosed. Breakers ll and 12 are provided, respectively,with operating members or handles 14 and 15 which project outward fromthe faces of their breakers and which are vertically movable downward tooff position and upward to on position either manually or by suitablemechanical means (not shown). Rectangular metal plates land 17,'whichprovide support for the interlock mechanism, are rigidly .providedtherein. If preferred, other means of providing support for theinterlockmechanism may be employed.

A first pair of levers or members 13 and 19, which have a rectangularconfiguration, are pivotally attached to plates 16 and 17,respectively,.by the bolts 20 :and 21. These levers are raised slightlyabove the surfaces thereof by the relatively thick spacer washers 22 and23, asFigs. 3 and 4 show, to afford clearance between the levers and theplates for those parts of the mechanism which attach to the levers.Tension springs 24 .and 25, which are'at tached at one of their ends tothe operating levers 18 and 19 by being hooked through small holesprovided therein, are anchored attheir other end to the threaded adjust--ment studs 26 and 27 which take into tapped openings by the springsuntil preventedfrom moving further by the stop posts 30 or 31 which arerigidlysecured to the plates'16 and 17 'asFigs. 3 and 4 show. Anglebrackets 32 and 33 are pivotally attached to operating levers 18 and 19by the pins 34 and 35 which are held in place by cotter keys, as Figs. 3and 4 show.

A second pair of levers or members 36 and 37, which have a polygonalcontour, are pivotally attached to the faces of the plates'l6 and 17 bythe bolts 38 and 39, and are raised to the level of the rectangularlevers 18 and 19 by relatively thick spacer washers such as thatdesignated by numeral 40 in Fig. 4. The levers 36 and 37 are arranged ontheir respective plates so that normally no portions of the levers liein the paths of travel of the breaker handles adjacent thereto. Thecontour of the levers is such that as the levers move from one positionto another they will not interfere *wit-h'other similarly attached toupper bracket 41 and lower bracket 1 33. As is clear from Fig. 4, theends of the latter brackets extend outward farther than the ends ofbrackets 32 and 42 so that rod 46 will overlie rod 45. The manner inwhich the rods are secured to the brackets, which is clear from Fig. 4,permits adjustments to be made so that when one of the levers 18 or 19is fully depressed by the breaker handle associated therewiththen'either of the levers 36 or 37 controlled thereby will be swungclear of the path of travel of the other breaker handle.

The above described interlocking mechanism operates in the followingmanner. Normally, as Fig. 1 shows, both breaker handles are disposed inthe downward off position thereby depressing the left ends of the levers18 and 19 and raising the right ends thereof. The tie rods attached tothe pivotable brackets carried by the rectangular levers are thus forcedupward causing the polygonal levers to be maintained clear of the pathof travel of their respective breaker handles. In this condition bothbreaker handles 14 and 15 are ready to be moved upwardly individually toon position.

Assume that breaker handle 15 is moved upwardly to on position as Fig. 2shows. Tension spring 25 draws rectangular lever 19 against stop post31. Simultaneously, rod 46 is pulled downwardly and polygonal lever 36is pivoted so that a portion thereof extends into the path of travel ofbreaker handle 14 thereby preventing handle 14 from being moved to onuntil breaker handle 15 is returned to oil? position and the interlockmechanism again assumes the position shown in Fig. 1.

Similarly, assuming that the breaker handle and interlock mechanism aredisposed as shown in Fig. 1, movement of breaker handle 14 upwardly toon position permits tension spring 24 to draw operating lever 18 againststop post 30. Simultaneously, rod 45 is forced downwardly andinterference lever 37 is pivoted so that a portion thereof extends intothe path of travel of breaker handle 15 thereby preventing handle 15from being moved to on until handle 14 is returned to off position andthe interlock mechanism again assumes the position shown in Fig. 1.

Thus, either one or the other, but not both, of the breakers may beenergized at any given time.

Although the invention is described in connection with verticallyadjacent circuit breakers whose handles move upwardly to on position, itcould be employed with breakers whose handles moved upwardly to ofi toprevent more than one breaker from being disconnected at any givenmoment, if such were desirable.

In addition, the invention may be employed with horizontally adjacentbreakers.

Furthermore, although the breakers are shown in Fig. 1 to be in directalignment, it will be understood that the interlock mechanism shownwould operate as well if the breakers were not exactly in directalignment but displaced therefrom, provided, of course, that the rodlengths were adjusted accordingly.

If desired, the invention may be employed with two breakers whoseoperating members do not travel identical distances in moving from oneto another position, provided that suitable changes are made in thelengths of the levers and the distances the latter are permitted topivot.

It will be noted that a portion of the interlock mechanism could beemployed separately with two breakers to control the order in which thebreakers are to be op- 4 i erated if such were desirable. Thus, usingonly lever 18, rod 45 and lever 37, disposed as shown in Fig. 1, ifhandle 15 were first moved to on then handle 14 could next be moved toon. But if handle 14 were first moved to on then handle 15 could not bemoved to on until handle 14 is returned to off position.

It is also apparent that the interlock mechanism disclosed herein may beconstructed of readily available materials, that it lends itselfadmirably to mass production, that it is foolproof in operation, andthat it is very well suited for use where space is at a premium, such aswhere the breakers are enclosed in a cabinet and only a small amount ofspace exists between the front of the breakers and the front panel ofthe cabinet (not shown). Finally, although it is contemplated that themechanism be fabricated of metal, it is obvious that other suitablematerials may be employed.

I claim:

1. In combination, a pair of adjacently mounted electrical devices eachhaving an operator movable between opposite extreme positions, and aninterlock mechanism comprising a biased first member held in a certainposition by the operator of one of said devices when the latter is inone of its extreme positions, a second member, and means mechanicallyinterconnecting said first and second members, said first member uponmovement of said operator of said one of said devices to its oppositeextreme position being biased to another position to move said secondmember into a position blocking movement of the operator of the other ofsaid devices into one extreme position thereof from its other extremeposition.

2. In combination, a pair of adjacently mounted circuit breakers each ofwhich has an operating member having a normal position and movabletherefrom to another position, a spring biased first movable membermaintained in a given position by one of said operating members when thelatter is disposed in its normal position, a second movable memberassociated with the other of said operating members and means forinterconnecting said first and second members whereby upon movement ofsaid one of said operating members from normal to its other positionsaid first member is biased a predetermined distance to efiectcorresponding movement of said sec ond member to prevent the other ofsaid operating members from moving from its normal to its otherposition.

3. In combination, a pair of adjacently mounted circuit breakers each ofwhich has an operating handle having a normal position and movabletherefrom to another position, at least one spring biased movableoperating lever maintained in a given position by one of said operatinghandles when the latter is disposed in its normal position, at least onemovable interference lever adjacent the path of travel of the other ofsaid operating handles, and means for interconnecting said operatinglever and said interference lever whereby upon movement of said one ofsaid operating handles from its normal to its other position saidoperating lever is biased a predetermined distance to effectcorresponding movement of said interference lever into the path oftravel of the other of said operating handles thereby preventing thelatter from being moved from its normal to its other position.

4. In combination, a pair of adjacently mounted circuit breakers each ofwhich has an operating member having a normal position and movabletherefrom to another position, a first movable member maintained in agiven position by one of said operating members when the latter isdisposed in its normal position, biasing means acting upon said firstmember, a second movable member associated with the other of saidoperating members, and means for interconnecting said first and secondmembers whereby upon movement of said one of said operating members fromits neutral to its other position said first member is biased apredetermined distance to effect corresponding movement of said secondmember thereby causing the latter to prevent the other of said operatingmembers from being moved from its normal to its other position.

5. In combination, a pair of adjacently mounted circuit breakers each ofwhich has an operating handle having a normal position and movabletherefrom to another position, supporting means, at least one operatinglever pivotally mounted on said supporting means and maintained in agiven position by one of said operating handles when the latter isdisposed in its normal position, biasing means acting upon saidoperating lever, at least one interference lever pivotally mounted onsaid supporting means adjacent the path of travel of the other of saidoperating handles, and means for interconnecting said operating leverand said interference lever whereby upon movement of said one of saidoperating handles from its normal to its other position said operatinglever is biased a predetermined distance to effect correspondingmovement of said interference lever into the path of travel of the otherof said operating handles thereby preventing the latter from being movedfrom its normal to its other position.

6. In combination, first and second adjacently mounted circuit breakerseach of which has an operating member normally disposed in one positionand movable therefrom to another position, supporting means associatedwith said breakers, a pair of first levers pivotally mounted on saidsupporting means, each of said first levers maintained in a givenposition by one of said operating members when the latter is normallydisposed in said one position, a pair of second levers pivotally mountedon said supporting means, each of said second levers disposed adjacentone of said operating members, means interconnecting the first leverassociated with said first breaker with the second lever associated withsaid second breaker, and means interconnecting the first leverassociated with said second breaker with the second lever associatedwith said first breaker, whereby movement of one of said operatingmembers from its normal to its other position effects pivoting of thefirst lever associated therewith a predetermined distance to eifectcorresponding pivoting of the second lever connected thereto into thepath of travel of the other of said operating members thereby preventingthe latter from being moved from its normal to its other position.

7. In combination, first and second adjacently mounted circuit breakerseach of which has an operating handle member having a normal positionand movable therefrom to another position, supporting means associatedwith said breakers, a pair of first levers pivotally mounted on saidsupporting means, each of said first levers maintained in a givenposition by one of said handle members when the latter is disposed inits normal position, biasing means attached to each of said firstlevers, a pair of second levers pivotally mounted on said supportingmeans, each of said second levers disposed adjacent the path of movementof one of said handle members, means interconnecting the first leverassociated with said first breaker with the second lever associated withsaid second breaker, and means interconnecting the first leverassociated with the second breaker with the second lever associated withthe first breaker, whereby upon movement of one of said handle membersfrom its normal to its other position said first lever is pivoted apredetermined distance by the biasing means attached thereto therebyelfecting pivoting of the second lever connected therewith into the pathof travel of the other of said handle members thus preventing the latterfrom being moved from its normal to its other position.

References Cited in the file of this patent UNITED STATES PATENTS1,337,895 French Apr. 20, 1920 1,796,229 Andersen Mar. 10, 19312,525,501 Taylor Oct. 10, 1950 2,604,796 Freese July 29, 1952 2,722,135Taylor Nov. 1, 1955 2,791,729 Allen et al. May 7, 1957

